Contrast Media in Cardiovascular System

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Questions and Answers

What is the primary central effect on the heart when a contrast media is injected?

Cardiac output

Myocardial contractility (correct)

Electrophysiology

Coronary blood flow

What is the primary effect on the peripheral vasculature when a large bolus of contrast media is delivered?

Generalized vasodilatation (correct)

Increased blood pressure

cardiac arrhythmia

Vasoconstriction

What is the effect of contrast media on plasma volume?

It decreases plasma volume

It has no effect on plasma volume

It expands plasma volume (correct)

It has a variable effect on plasma volume

What is the effect of contrast media on blood coagulation?

It has anti-coagulant properties Signup and view all the answers

What is the effect of high osmolality contrast media on smooth muscles?

It causes vasodilatation Signup and view all the answers

Why does contrast media injection into the coronary arteries have a marked depressant effect on cardiac pump function?

Due to the combination of direct and indirect neurally mediated effects Signup and view all the answers

What is the effect of contrast media on coronary blood flow?

It increases coronary blood flow by a steal phenomenon Signup and view all the answers

Why are highly concentrated contrast media used to visualize small cardiac vessels?

Because they have high iodine concentration Signup and view all the answers

What happens to cardiac contractility initially after the injection of ionic contrast media?

It decreases Signup and view all the answers

What happens to the calcium to sodium ratio after the injection of ionic contrast media?

It may not change Signup and view all the answers

Why does cardiac contractility decrease after the injection of ionic contrast media?

Due to the binding of calcium ions to the anionic compound Signup and view all the answers

What happens to the extracellular fluid after the injection of contrast media with higher osmolality than plasma?

It moves from the extravascular space into the capillaries Signup and view all the answers

What is the effect of cellular dehydration on cardiac contractility?

It increases contractility Signup and view all the answers

Why does nonionic contrast media not cause depressed cardiac contractility?

Because it does not bind to calcium ions Signup and view all the answers

What is the effect of nonionic contrast media on cardiac contractility?

It increases contractility Signup and view all the answers

What is the effect of contrast media injection on hydrogen concentration?

It increases hydrogen concentration Signup and view all the answers

What is the effect of hyperosmolar contrast solution on cardiac vessels?

Vasodilatation Signup and view all the answers

What is the result of injecting CM into a coronary artery?

All of the above Signup and view all the answers

What is the effect of hypertonic CM on the heart?

Bradycardia Signup and view all the answers

What is the effect of CM on vascular endothelium?

Irritation or damage Signup and view all the answers

What is the clinical symptom of endothelial damage?

Sensation of heat and pain Signup and view all the answers

What increases the incidence of post-phlebographic thrombosis?

Increasing chemotoxicity Signup and view all the answers

Why is thrombosis seen less in arm veins than leg veins?

Higher fibrinolytic activity in arm veins Signup and view all the answers

What can reduce the incidence of post-phlebographic thrombosis?

Using low osmolality CM Signup and view all the answers

What happens to the cells when exposed to high osmolality Contrast Media?

They shrink and pull apart Signup and view all the answers

What is the effect of ionic Contrast Media on cardiac contractility?

It initially decreases and then increases contractility Signup and view all the answers

What is the effect of Contrast Media on coronary perfusion?

It increases perfusion Signup and view all the answers

What is the effect of Contrast Media on conduction in the heart?

It slows conduction Signup and view all the answers

What is the effect of Contrast Media on peripheral vessels?

It causes vasodilatation and decreased blood pressure Signup and view all the answers

Why is it important to hydrate patients before Contrast Media administration?

To reduce the risk of nephrotoxicity Signup and view all the answers

What is the effect of Contrast Media on red blood cells?

They become dehydrated and deformed Signup and view all the answers

Why is it recommended to hydrate patients with up to 2L of normal saline before Contrast Media administration?

To reduce the osmotic activity of Contrast Media Signup and view all the answers

Why should administration of contrast media during pregnancy be limited?

Because it should only be performed for essential indications Signup and view all the answers

What percentage of contrast media is excreted by the kidneys in the first hour?

30% Signup and view all the answers

Why can water-soluble contrast media pass through the glomerular pores?

Because they are small in size and not bound to protein Signup and view all the answers

What is the percentage of contrast media excreted by the kidneys in the next 6 hours?

70-75% Signup and view all the answers

What happens to contrast media excretion in patients with impaired kidney function?

Extrarenal excretion is more pronounced Signup and view all the answers

What is the recommendation for breastfeeding after contrast media administration?

Breast milk should not be fed to the infant for 3 days Signup and view all the answers

Study Notes

Contrast Media Cardiovascular System

Primary central effects on the heart:
Myocardial contractility
Electrophysiology
Coronary blood flow
Primary effects on the peripheral vasculature:
Vasodilatation
Hypotension
Tachycardia
Contrast Media (CM) expands plasma volume and has anti-coagulant properties
CM causes generalized vasodilatation, resulting in hypotension and tachycardia, mainly due to hyperosmolality mediated effect on smooth muscles
Effects on the heart are greatest when injected directly into the coronary arteries
Marked depressant effects on cardiac pump function, which are dose-dependent and cumulative

Electrophysiology of the Heart

CM injection into a coronary artery may result in disturbances of electrophysiology, leading to ECG changes
Effects depend on CM osmolality and changes in cation concentrations
Lower osmolality results in fewer changes, and nonionic CM has fewer changes
Tachycardia, bradycardia, asystole, and other arrhythmias can occur
Injection of hypertonic CM results in slowing of electrophysiology, leading to bradycardia

CM and Blood Vessel Walls

CM can act on vessel walls and contents, causing irritation or damage
Clinical symptoms include sensation of heat and pain, and initiation of thrombus formation
Endothelial damage increases with:
- Increasing chemotoxicity
- Increasing osmolality
- Increasing contact time between endothelium and CM
Consequences of endothelial damage:
- Thrombosis is more likely
- Large molecules can pass through the endothelium, causing problems

Summary of CM Effects on the Cardiovascular System

Cardiac contractility:
- Ionic CM: contractility decreases then increases
- Nonionic CM: contractility only increases
Coronary perfusion: increases, but may lead to a steal effect
Conduction: delayed
Heart rhythm: all types of arrhythmias are possible
Peripheral vessels:
- Pain and heat caused by hyperosmolality of CM
- Vasodilatation causes decreased blood pressure
Endothelium:
- Affected by hyperosmolality and chemotoxicity of CM
- Cells become dehydrated, shrink, and junctions become leakier
Red blood cells:
- Become dehydrated and deformed
- Cannot pass through capillaries easily, increasing resistance and workload on the heart
Capillaries:
- Endothelium becomes leaky as cells shrink and junctions open
Coagulation:
- CM inhibits coagulation, more pronounced in ionic CM

Contrast Media and Dehydration

All CM are osmotically active substances that absorb water from their environment
Patients should be adequately hydrated with up to 2L of normal saline before CM administration
Electrolyte loss must be compensated for previously
Dehydration increases the risk of nephrotoxicity

Clearance of Contrast Media

Kidney: water-soluble CM is excreted by glomerular filtration
Small size of CM molecules allows passage through glomerular pores
CM molecules are not bound to protein (albumin)
About 30% of CM is excreted by kidneys in the first hour, and 70-75% in the next 6 hours
Other routes of excretion (less than 5%): sweat, tears, saliva, bile, and pancreas
In patients with impaired kidney function, extrarenal CM excretion is more pronounced, and there is increased protein binding for these substances

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Description

This quiz covers the effects of contrast media on the heart and peripheral vasculature, including changes in myocardial contractility, coronary blood flow, and blood pressure.